This invention relates to a magnetron, and more particularly to a structure for improving magnetic field distribution in an interaction space.
Magnetrons used for a microwave oven generate microwave energy from a magnetic field which is generated in an interaction space of a magnetic device. In general, the magnetron is comprised of magnets, yokes connecting magnetically with each magnet, pole pieces disposed at both ends of a magnetron body, a plurality of spaced radial vanes projecting inwardly within an anode cylinder and a cathode coaxially disposed in the anode cylinder. It is necessary for stabilizing the oscillation of the magnetron tube that the direction of the magnetic field in the interaction space generated by the magnetic device acting onto the magnetron body should coincide exactly with the direction of the anode cylinder axis and that the magnetic field distribution should preferrably be uniform. The pole piece is provided for this purpose, so as to make the magnetic field uniform and parallel to the anode cylinder axis. It is however difficult actually to make the magnetic field sufficiently uniform. Especially, this defect appears in magnetrons which have magnets within the magnetron body and do not have a pole piece for adjusting the magnetic field distribution. This type magnetron has a magnet which is disposed closely to an interaction space between the ends of vanes and the cathode and the magnet may be small for obtaining an effective magnetic device so the uniformity of the magnetic field degrades. Therefore the object of this invention is to obtain an improved magnetron having a field correcting means.